[DO NOT MERGE] apps/system/i2c : i2c test tool return value fixed

[anjana348]

[TEMP FIX] To run i2c test tool, i2c transfer returns length of data, so modified check condition Usage example -

1. i2c help - to get supported list of commands

For i2c write and read . Device addr 0x50, bus 1, reg addr 0x23, data width 8 bit, frequency 100000 and value 0x00 TASH>>i2c set -a 0x50 -b 1 -r 0x23 -w 8 -f 100000 0x00 TASH>>WROTE Bus: 1 Addr: 50 Subaddr: 23 Value: 00 TASH>>i2c get TASH>>READ Bus: 1 Addr: 50 Subaddr: 00 Value: 7d